The present invention is directed to a method and a device for measuring the cutting force and limiting the overload of the cutting force in a platen press.
At the present, it is known to measure the cutting force of a platen press by utilizing a sensor, for instance a deformation reading sensor which is located on one of the lateral frames of the machine. Thus, when the press is set under pressure for cutting a cardboard sheet, the forces acting on the frame increase and the sensor reads the deformation in the frame member and converts this into an electrical pulse which is then transmitted so that it can be displayed as a value relative to the cutting force.
Nonetheless, this kind of measure does not show the forces which readily act in the press since it was planned to measure them directly on the toggle transmitting the motion to the shiftable bed or platen used in this type of press. In that case, a set of four sensors, each one mounted on one of the toggles, is used. Nonetheless, if this solution is more satisfying than the first cited one, it does not yet allow the measuring of the real forces acting in the press during the cutting operation. Indeed, the lack of accuracy of these measures would allow the raising of the punctual overloads which in certain cases might destroy various members or parts of the press. The second example avoids the occurrence of the overloads, but the accuracy of the measuring is insufficient when the cutting force is low so that the measuring of the real force acting in all operation areas of the cutting unit is not warranted.